This invention relates to vacuum booster devices for boosting a master cylinder of automotive hydraulic brake, clutch or the like with vacuum pressure and, more particularly, to improvements in those of the type comprising a booster shell divided into a front bowl and a rear bowl, a booster piston accommodated in the booster shell, and tie rods extending through the booster piston for connection of the front and rear bowls.
Conventionally, when a vacuum booster device of the above type installed in an automobile operates the master cylinder, frontward thrust loaded on the master cylinder is directly transmitted to and supported on the automobile body through the tie rods and not on the booster shell, so that the booster shell can be made thinner and lighter.
In assembling this booster device, the rear end of the tie rod is connected to the rear bowl first, and, after the front bowl is fitted to the rear bowl, front end of the tie rod is connected to the front bowl, However, for easily assembling both the bowls without any interference by the tie rods, the tie rods should firmly be fixed upright at prescribed positions in the rear bowls.